Building the Phase 45

[KerryF]

Ook so heres another Phase 45 build thread.  I will post my progress here.

So far I have just gotten together the parts.  I know these questions have been answered, but I like getting a straight answer thats not from the past (strange I know).  I still need a 3.9m resistor (can I use a 3.3m or 4.7m?) and a 2.4k (can I use a 2.2k?).  I dont have any 2N5458s right now, but what are some other FETs I can use for good results?  I am using the stripboard with the mods. http://aronnelson.com/gallery/album28/MXR_Phase_45?full=1

Any other useful suggestions for this one? 

[slacker]

The 2.4k (R24) is the current limiting resistor for the LED. Any similar value resistor will work fine. A 3M3 would probably be fine for R18, or maybe put a 470k in series with the 3M3 to give 3.7M.
The circuit will work with different jfets, but might need some adjustments. Do a search there's loads of good information about using different jfets in this.

[KerryF]

thanks SOOO much slacker for answering that for me. 

Still, anyone tell me a good replacement for the FET?

[mydementia]

I played the fet matching game with both my Phase45 and Phase90...didn't really like the 'right' fets... now, both have randomly selected J201's - sounds great!!  Light 'woosh' on the Phase45 - heavier 'woosh' on the Phase90 (as it should be!).  Still haven't tackled the Phase100 yet... that's a LOT of parts!

Mike

PS> If anyone is interested in a built/working Phase45 (from Torchy's vero layout with univibe mod), send me a PM (ever since building the 90, I don't use the 45).

[KerryF]

Thanks!  I will try J201s.  I have like 30-40 so I will be able to match good.  I cant wait to finish this thing!  I am loving how it will do a sortof Univibe and Phase!

[KerryF]

Another question:

*Mod #4 is two 8k2 resistors in parallel instead of a 4k1.  Whats the point of this?  Why not just use the 4k1?

[slacker]

You get different series of "preferred" resistor values and you can't get a 4k1 resistor. Have a look at this page for an explanation http://www.logwell.com/tech/components/resistor_values.html
For example the resistors I use are from the E12 series and the closest values are 3k9 and 4k7.
The R23 resistor pair sets the fastest speed of the LFO and I don't know why 4k1 was chosen originally instead of one of the standard values perhaps 3k9 was just too fast and 4k7 not quite fast enough. If you're going to use the phaser mainly for slower sounds then it doesn't make any difference.

[KerryF]

Ok thanks again Slacker.  I am going to take some pictures of it so far right now...

[KerryF]

Pictures!:




EDIT:
With the JFET Matcher ( http://aronnelson.com/gallery/album75/Jfet_Matcher_6 ), can I use a TLC071 instead of the TL071?

[markm]

1800....
If ya need a JFET matcher, I have a layout for it in my gallery! 

[KerryF]

Yea I saw it and want to use it, but can I replace the IC in yours for a TLC071 or another chip?

Thanks

[markm]

Yea I saw it and want to use it, but can I replace the IC in yours for a TLC071 or another chip?

Thanks

TL071 would work fine.

[KerryF]

What about the TLC071 though?  What about a TL072?

I have it breadboarded, but im waiting for the IC...

[Seljer]

TL071 = single opamp

so you can use prettymuch any other single opamp
you'd have to find/make a new layout to use a TL072

[KerryF]

k.  my TLC072 is working right.  Can someone give me some type of example of a Voltage reading I should get?  Also, does it matter which multimeter cable goes to what DMM place on the layout?

[markm]

Where you hook the DMM to isn't an issue.
Go here>>>>>>>>http://www.geofex.com/
and read all the info aon JFET matching on R.G.'s site. Very informative and all U need to know and then some!

[KerryF]

Ok, I just matched the J201s.  Heres some of my closest combos I got:

61.7mV
61.6mV
56.6mV
57.5mV
47.7mV

87.1mV
86.3mV

192.2mV
192.8mV
191.4mV

-56.1mV
-54mV
-58.7mV

Now which set of two from there is the best for this?

And, the 5.1V Zener Diode, can it be a 12V Zener Diode?

[KerryF]

^-Bump...

[slacker]

I'm not sure which of the jfets set would be best. When I made mine I just used sockets for the jfets and mixed and matched different ones until I got a pair that sounded good.

You can't use a 12v zener. The zener sets the bias voltage for the opamps and the fets, you need one about 1/2 the supply voltage. So a 5.1 or 4.7 would work, I think you can even use a 3volt one. If you haven't got any suitable zeners you can use a couple of red leds and a silicon diode in series like in the easyvibe.
Heres the schematic http://www.hollis.co.uk/john/easyvibe.jpgLook at the bit far left.
You could replace the zener with a 10k resistor, which will give you a 1/2 supply bias voltage. This will work fine if you only use a power supply with the pedal. If you use a battery as the voltage drops the bias voltage will change which might stop the fets working, or at least change the sound of the pedal.

[KerryF]

Thanks slacker.  I will try different ones.

But if you were thinking in terms of what should sound the best, would high, medium, or low mV JFETs work better?

Medium Sets:
*56.mV and 56.mV
*61.3mV and 61.3mV

High Set:
*192.1mV and 192.5mV